SUVOROV, S. G. Coleman Principles and Krasnosel’skii Genus in Eigenfunction Problems. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 53, n. 7, p. 983–992, 2001. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4318. Acesso em: 6 dec. 2025.